US 7,621,326 B2Granted

Petroleum extraction from hydrocarbon formations

OwnerHenry B Crichlowinventor

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Abstract

Recovery of viscous hydrocarbon by hot fluid injection from subterranean formations is assisted by using a specially designed and under-reamed vertical well to form a central production cavity; combined with a plurality of specially perforated horizontal wells drilled from the surface down to the producing formation, and then drilled laterally to intersect and be operatively connected to the central production well cavity. These continuous horizontal uniwells™ behave as single wells with two wellheads, each with multiple injection-production perforation pairs, between which the controlled flow of hot oil via a specialized annular communication zone. The production process is controlled by modulating the hot oil flow where the wellbore fluids act as a hydraulic “P-trap” seal limiting steam bypass. The hot displaced oil is allowed to drain from the lateral horizontal wells in to the central collection cavity.

Claims34

Dependent claims

A method for recovering hydrocarbons from a subterranean formation containing viscous oil, oil shale, tar sands or other heavy hydrocarbons;

the method comprising the steps of:
(a) drilling a central wellbore down to the hydrocarbon bearing formation by penetrating the formation and the under-burden zones;
(b) reaming out a section of the central wellbore to form a viably located production cavity;
(c) drilling at least one additional wellbore vertically from the surface and then laterally through the said formation to connect said additional wellbore to the said production cavity and further comprising the step of installing a means for active control of the back pressure in this additional wellbore;
(d) providing a plurality of perforations in the said additional wellbore at pre-selected intervals;
(e) installing a downhole wellbore packer between upper and lower perforations;
(f) implementing a means for forming an annular zone of increased fluid conductivity near the said additional wellbore in the said formation;
(g) heating the said formation by injecting a displacing fluid into the formation;
(h) collecting oil and water in the said production cavity;
(i) lifting the produced fluids and displaced fluids to the surface by using a fluid recovery system.

7 more elements

Dependencies are inferred from the claim text.

Facts

Application: 11/279,681Filed 13 Apr 2006 · us provisional application
Priority: 1 Feb 2006
Published: US 2007/0175638 A12 Aug 2007
Granted: 24 Nov 2009
Term ends: Not estimatedThe source records don’t support an estimate.

Classification3 codes

E21B 43/305
Specific pattern of wells, e.g. optimising the spacing of wells: comprising at least one inclined or horizontal well
E21B 43/24
Enhanced recovery methods for obtaining hydrocarbons: using heat, e.g. steam injection
E21B
Earth or rock drilling